Organic Solar Cells: Solution‐Processable Reduced Graphene Oxide as a Novel Alternative to PEDOT:PSS Hole Transport Layers for Highly Efficient and Stable Polymer Solar Cells (Adv. Mater. 42/2011)

Yun, Jin‐,Mun,Yeo, Jun‐,Seok,Kim, Juhwan,Jeong, Hyung‐,Gu,Kim, Dong‐,Yu,Noh, Yong‐,Jin,Kim, Seok‐,Soon,Ku, Bon‐,Cheol,Na, Seok‐,In WILEY‐VCH Verlag 2011 Advanced Materials Vol.23 No.42

<P>Solution‐processable reduced graphene oxide as a hole‐transporting layer for highly efficient and stable organic solar cells is reported on page 4923 by Dong‐Yu Kim, Seok‐In Na, and co‐workers. Introduction of a newly reduced graphene oxide by simple solution processing into solar cells dramatically raises the cell efficiency and cell life‐time. The results will allow full use of chemically reduced graphene and will advance the realization of carbon‐based printable optoelectronic devices. </P>

장방형내 저온 단일 수평 원관 주위의 동결현상에 관한 실험적 연구

정현철,윤재원,장원택,전승배,이동석,김병철 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

An experimental study on water in a rectangular cavity with a horizontal cooling tube was carried out to investigate the flow character and thermal behavior in the system. Each experiment was performed with variation of initial temperature and cooling tube temperature. When the cooling tube temperature was -4℃, the supercooling phenomenon was observed regardless of the initial water temperature. And the case of cooling tube temperature was -6℃ with initial temperature was below 4℃, the supercooling phenomenon was also observedin the large region of the test section. When the cooling tube temperature was -10℃, the local region of supercooling phenomenon was observed during the freezing process. And the higher initial temperature was, the higher supercooling degree and the less difference of the ice thickness between upward and downward was observed. It is shown that by controllingthe supercooling phenomena and the cooling tube temperature, it would lead to an increase efficiency of ice making.

수직 냉각면이 있는 정방형내 성층유체의 열적거동에 관한 실험적 연구

정현철,윤재원,장원택,전승배,이동석,김병철 朝鮮大學校 機械技術硏究所 2007 機械技術硏究 Vol.10 No.1

This study was investigated by experimentals on the thermal behavior of stratified fluids in the square cavity with the vertical cooling surface by variation of initial temperature and cooling surface temperature and concluded as follows: 1. When the cooling surface temperature of the square cavity was -4℃. the supercooling phenomena was occurred every times regardless initial temperature of fluids and when -6℃ freezing was begun with out supercooling phenomena. 2. The higher the initial temperature was, the longer supercooling phenomena duration was, and the longer the supercooling phnomena was, the higher the temperature of the upper fluids was. 3. When the supercooling phenomena of water was occurred, the rate of temperature decrease of silicon oil was higher and when there was no supercooling phenomena, it was almost same the rate of temperature decrease.

SWS 490B 강의 피로균열 진전시 음향방출 거동과 파단면 관계

鄭中采,尹東珍,朴徽立,金基福,李承錫 대한금속재료학회 2002 대한금속·재료학회지 Vol.40 No.8

The objective of this study was to investigate the effect of AE activities during fatigue test. Laboratory experiment was carried out to identify AE characteristics of fatigue cracks for compact tension specimen. The relationship between a stress intensity factor and AE signals activity was discussed. From the experimental results, the features of specific parameters such as the length of crack growth, the AE energy and the AE peak amplitude, showed similar trend in their increase as the stress intensity factor increased. The fracture surface of test specimens revealed both intergranular fracture and transgranular fracture. Size and density of slip band were varied as the stress intensity factor increased and AE activities were different according to the slip band shape.

3차원 전산화단층촬영 영상을 이용한 얼굴 연조직 두께 계측

정호걸,김기덕,한승호,신동원,허경석,이제범,박혁,박창서 대한구강악안면방사선학회 2006 Imaging Science in Dentistry Vol.37 No.1

Purpose : To evaluate accuracy and reliability of program to measure facial soft tissue thickness using 3D computed tomographic images by comparing with direct measurement. Materials and Methods : One cadaver was scanned with a Helical CT with 3 mm slice thickness and 3 mm/sec table speed. The acquired data was reconstructed with 1.5 mm reconstruction interval and the images were transferred to a personal computer. The facial soft tissue thickness were measured using a program developed newly in 3D image. For direct measurement, the cadaver was cut with a bone cutter and then a ruler was placed above the cut side, The procedure was followed by taking pictures of the facial soft tissues with a high-resolution digital camera. Then the measurements were done in the photographic images and repeated for ten times. A repeated measure analysis of variance was adopted to compare and analyze the measurements resulting from the two different methods. Comparison according to the areas was analyzed by Mann-Whitney test. Results : There were no statistically significant differences between the direct measurements and those using the 3D images (p>0.05). There were statistical differences in the measurements on 17 points but all the points except 2 points showed a mean difference of 0.5 mm or less. Conclusion : The developed software program to measure the facial soft tissue thickness using 3D images was so accurate that it allows to measure facial soft tissues thickness more easily in forensic science and anthropology. (Korean J Oral Maxillofac Radiol 2006; 36 : 49-54)

저선량 감마선 조사가 왕겨의 항산화능에 미치는 영향

정석문,김정한,김동열,육홍선,변명우,이승철 慶南大學校 附設 基礎科學硏究所 2002 硏究論文集 Vol.16 No.-

왕겨에 200, 400, 600, 800 및 1000 Gy의 저선량의 감마선을 조사하여 항산화능의 변화를 관찰하였다. 총 페놀 화합물의 양은 무처리구의 경우 0.184 mM를 나타내었고, 200 Gy로 감마선을 조사하였을 때는 0.215 mM로 약간 증가함을 보였으나 이후 차츰 감소하였다. 전자 공여능은 무처리구에 비해 처리구의 경우 조사 선량별로 조금씩의 차이만 있을 뿐, 조사 선량에 대한 왕겨의 전자 공여능은 유의적인 큰 변화 없이 비슷한 활성을 보였다. Fe^2+-ions 킬레이팅 활성은 무처리구의 경우 68.25%를 나타내었으며, 200, 400, 600 및 800 Cy 에서는 각각 86.45, 85.61, 86.65 및 82.84%로서 무처리구보다는 증가함을 보였으나, 1000 Gy에서는 74.67%로 감소하였다. 지질 과산화 억제능은 무처리구에 비해 처리구는 약간의 증가를 보였으나 효과는 미비하였다. We studied the effect of small-dose of γ-irradiation to rice hull(RH) for its antioxidant ability. The RH was treated with 200, 400, 600, 800, and 1000 Gy of γ-ray at 70 Gy/min. Total phenol amount of unirradiated RH was 0,184 mM, after irradiation at 200 Gy it increased to 0,215 mM, while irradiation above 400 Gy up to 1000 Gy decreased that to unirradiated level. The electron donating ability of RH did not show significant change depend on irradiation. The chelating ability for Fe^2+ of unirradiated RH was 68.25 %, while that of 200, 400, 600 and 800 Gy irradiated RH showed 86.45, 85.61, 86.65 and 82.84 % respectively, but, 1000 Gy was decreased to 74.67 %. According to TBARS analyses, inhibition ability of lipid peroxidation by RH was not affected by γ-irradiation.

근첨하 분절 골절단술을 병행한 Ⅲ급 양악 전돌증의 교정치료 증례

정미향,남동석 대한치과교정학회 1998 대한치과교정학회지 Vol.28 No.3

양악 전돌은 흔히 접하는 부정교합 증례로서, 대부분 상하순의 전돌에 의한 안모 심미성의 손상을 주소로 내원한다. 이러한 증례는 제1소구치를 발거하고 그 공간을 이용하여 전치부를 견인하여 치료하는 경우가 많으며, 성공적인 치료결과를 얻을 수 있다. 그러나, 성인 환자의 경우에는 환자의 협조도 불량으로 인한 악외 고정원 사용의 불량, 치료기간의 장기화, 치조골이 충분하지 못한 경우등에 있어서의 치근 흡수량의 증가, 구외 장치 사용으로 인한 환자의 사회심리적 부담감등의 부작용이 있다. 이의 해결방안의 하나인 근첨하 분절 골절단술은 고정원의 절대 보존, 치료기간의 단축, 구외 고정원 사용 필요성 제거 및 이를 통한 환자의 협조도 증가 등의 장점을 가지고 있다. 이에, 제 1소구치 발거 및 이 부위를 이용한 근첨하분절 골절단술을 병행하여 치료한 치아치조 전돌의 증례를 치료 전후의 두부 방사선 계측 사진 및 연구 모형을 통해 비교분석하여 변화를 살펴보고. 이의 장단점을 고찰해 보도록 하고자 한다. Bimaxillary protrusion can be treated effectively in growing patients and in adults with conventional orthodontic therapy. However, In the adult patient, combined surgical and orthodontic treatment modalities may offer distinct advantages over such conventional therapy. In those cases complicate by vertical jaw dysplasia, sagittal dysplasia, or transverse skeletal discrepancy in addition to bimaxillary protrusion, the possibilities of obtaining successful results through orthodontic treatment alone greatly diminish. Surgical retraction of both maxillary and mandibular anterior segments with subapical osteotomies and ostectomies in the extraction site may be a good treatment alternative. Treatment time and possible adverse effects of lengthy orthodontic therapy may be reduced and optimum esthetic improvement may be facilitated. On the following cases, patient who had bimaxillary protrusion with Angle Class III malocclusion was treated with combined orthodontic - surgical therapy by anterior subapical segmental osteotomies.

농가용 저온저장고의 제어변수에 따른 성능평가

김석우,김성만,현명택,최동호,고정삼,박영하 제주대학교 공과대학 첨단기술연구소 2001 尖端技術硏究所論文集 Vol.12 No.2

The low temperature storage method has been used to increase the value of agricultural products by reducing quality deterioration and controlling respiration rate. The respiration rate of agricultural products depends on several factors such as temperature, moisture, gas composition and microbe inside the storage room. Among that temperature is the most important factor, which affects respiration rate and causes severe damage. The results obtained from these experiments are that electric consumption is decreased as setting temperature is decreasing and temperature deviation is increasing. In the ventilation experiment, the case ventilated four times a day(every six hours a day) with ten minutes operation each time, was inspected require as much electric consumption as non-ventilation case.

주성분 회귀분석 및 인공신경망을 이용한 AE 변수와 응력확대계수와의 상관관계 해석

윤동진,김기복,정중채,박휘립,이승석 한국비파괴검사학회 2001 한국비파괴검사학회지 Vol.21 No.1

AE 신호와 재료의 기계적 물성과의 관계를 정량적으로 제시할 수 있는 방법을 개발하였다. 재료의 여러 가지 기계적 성질들 중 피로균열 거동에 관련된 응력확대계수를 중심으로 AE 신호와 같은 다변량 데이터의 처리에 많이 사용되고 있는 주성분 회귀분석과 비선형적 문제 해결에 적합한 신경회로망 기법을 이용하였다. 이를 위하여 강교량 부재인 SWS490B 강에 대한 피로균열전파 실험을 수행하였으며 표준 CT 시편에 대한 피로균열진전 시 발생하는 AE 신호의 각 변수와 응력확대계수와의 관계를 고찰하였다. 통계분석 방법인 변수선택법을 적용한 결과 AE 카운트(RC), 에너지(EN), 신호지속시간(ED)의 각각에 대한 유의성이 높은 것으로 나타났으나 전반적으로 전체 AE 변수를 모두 이용할 경우 통계적 유의성이 높은 것으로 나타났다. 부재의 반복하중 시 발생하는 피로균열진전을 정량적으로 도출할 수 있는 응력확대계수 추정모델을 개발하고 평가하였다. 미지 시료에 대하여 개발된 모델의 응력확대계수 예측 성능을 분석한 결과 주성분 회귀모델과 인공신경망 모델 모두 우수한 예측성능을 나타내었으나 전반적으로 인공신경망 모델이 주성분 회귀모델보다 다소 양호한 것으로 분석되었 다. The aim of this study is to develop the methodology which enables to identify the mechanical properties of element such as stress intensity factor by using the AE parameters. Considering the multivariate and nonlinear properties of AE parameters such as ringdown count, rise time, energy, event duration and peak amplitude from fatigue cracks of machine element, the principal component regression(PCR) and artificial neural network(ANN) models for the estimation of stress intensity factor were developed and validated. The AE parameters were found to be very significant to estimate the stress intensity factor. Since the statistical values including correlation coefficients, standard error of calibration, standard error of prediction and bias were stable, the PCR and ANN models for stress intensity factor were very robust. The performance of ANN model for unknown data of stress intensity factor was getter than that of PCR model.

직장에 발생한 원발성 악성 흑색종 1예

이석주,김광일,김동호,김홍성,우상민,최덕례,정현용 충남대학교 의과대학 지역사회의학연구소 1997 충남의대잡지 Vol.24 No.1

An extremely rare case of primary melanoma involving only rectum is reported. This 59 year-old male patient was admitted to the hospital because of hematochezia, difficulty of defection. Endoscopic examination and radical excision showed polypoid lesion with ulceration which measured 6x6x3cm in 2cm from the anal verge. Histopathologic, H&E stain and electron microscopic examination(EM) were performed from endoscopic biopsies and excisional mass. We are reporting a case primary rectal melanoma with brief review of literature.